/Engine/Source/Runtime/Engine/Public/SceneManagement.h
void Initialize ( float InBlendFraction, const FSHVectorRGB3 * InIrradianceEnvironmentMap, const FSHVectorRGB3 * BlendDestinationIrradianceEnvironmentMap, const float * InAverageBrightness, const float * BlendDestinationAverageBrightness, const [FLinearColor](API\Runtime\Core\Math\FLinearColor) * InSpecifiedCubemapColorScale )